Light sources are frequently needed for various scientific uses, particularly for spectroscopy and for photometric uses. Continuous spectral distribution of wave lengths in the visible light are provided by incandescent lamps or by Xenon lamps. The spectrum of the Xenon lamps, within the visible light range, is similar to the spectrum of a black body radiator of between 6200.degree. to 6500.degree. K. Due to the high operating pressure of such Xenon discharge lamps, the Xenon spectral lines are broadened and flattened out, and are overlapping to form an essentially continuous spectral output.
Xenon gas discharge lamps require substantial power input and the spectral distribution, as well as the operating characteristics of known Xenon lamps are difficult to control.